### In this module, you will learn:

- the definition of work done
- how to calculate work done

### Resources to help you:

**Textbook:**page 122 and 123

# Work Done

Work is done when an object **moves **while a **force **is being exerted on it.

Work done is measured in the unit of **joule **(**J**) or **newton metre** (**Nm**). J**oule is the SI unit **of work done.

When the pulling force moves the box, work is done.

Credit: @iimage via YayImages (edited)

## Work is done if the three conditions apply

- There is a
**force**acting on an object. - The object
**moves**. - The
**movement**of the object is in the**same direction of the force.**

## Calculating Work Done

**w**ork done = **F**orce x **d**istance moved in direction of the force

where **Force **is measured in **newtons (N)** and **distance **in **metre (m)**

**If distance is in not in m (e.g. cm or mm), it has to be converted to metre first.**

## Watch the video

See how to use the formula to calculate Work Done

Source: https://www.youtube.com/watch?v=JHEmPZ-YnrU

You can change the speed to 0.75x to make it easier to listen.

## A little note on doing your working

In Science, we are only looking for very simple working and not the calculation itself as you are allowed to use a calculator.

**Step 1:** Write the formula, **w = F x d**

**Step 2:** **Substitute **the value for **force (F) in newtons** and **distance (d) in metres (same direction as the force)**

**Step 3:** Use a **calculator **to do the calculation** **

**Step 4:** Write the **answer **with the **unit**

** **

**e.g. ** **w = f x d**

** ** **= 50 N x 5 m**

** ** **= 250 J**

**That is really you really need to write as your working.**

** **

## Working if distance is not in metre

If the distance is not in metre, you will have to convert it.

1 m = 100 cm

1 m = 1000 mm

**For example, **

Calculate work: A 100 Newton force is applied to move an object a distance of 500 centimetres across the floor?

First change the 500 centimetres into metre.

**1 m = 100 cm**

**500 cm ** **= 500 / 100**

**= 5 m **

**w ** **= F x d**

** = 100 N x 5 m**

** = 500 J **